RDS Tutorial (VBScript)

Άρθρο
11/18/2022

This is the RDS Tutorial, written in Microsoft Visual Basic Scripting Edition. For a description of the purpose of this tutorial, see the RDS Tutorial.

Important

Beginning with Windows 8 and Windows Server 2012, RDS server components are no longer included in the Windows operating system (see Windows 8 and Windows Server 2012 Compatibility Cookbook for more detail). RDS client components will be removed in a future version of Windows. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. Applications that use RDS should migrate to WCF Data Service.

In this tutorial, RDS.DataControl and RDS.DataSpace are created at design time - that is, they are defined with object tags, like this: <OBJECT>...</OBJECT>. Alternatively, they could be created at run time with the CreateObject Method (RDS) method. For example, the RDS.DataControl object could be created like this:

Set DC = Server.CreateObject("RDS.DataControl")  
   <!-- RDS.DataControl -->  
   <OBJECT   
      ID="DC1" CLASSID="CLSID:BD96C556-65A3-11D0-983A-00C04FC29E33">  
   </OBJECT>  
  
   <!-- RDS.DataSpace -->  
   <OBJECT   
      ID="DS1" WIDTH=1 HEIGHT=1  
      CLASSID="CLSID:BD96C556-65A3-11D0-983A-00C04FC29E36">  
   </OBJECT>  
  
   <SCRIPT LANGUAGE="VBScript">  
  
   Sub RDSTutorial()  
   Dim DF1

Step 1 - Specify a server program

VBScript can discover the name of the IIS Web server it is running on by accessing the VBScript Request.ServerVariables method available to Active Server Pages:

"https://<%=Request.ServerVariables("SERVER_NAME")%>"

However, for this tutorial, use the imaginary server, "yourServer".

Note

Pay attention to the data type of ByRef arguments. VBScript does not let you specify the variable type, so you must always pass a Variant. When using HTTP, RDS will allow you to pass a Variant to a method that expects a non-Variant if you invoke it with the RDS.DataSpace object CreateObject method. When using DCOM or an in-process server, you must match the parameter types on the client and server sides or you will receive a "Type Mismatch" error.

Set DF1 = DS1.CreateObject("RDSServer.DataFactory", "https://yourServer")

Step 2a - Invoke the server program with RDS.DataControl

This example is merely a comment demonstrating that the default behavior of the RDS.DataControl is to perform the specified query.

<OBJECT CLASSID="clsid:BD96C556-65A3-11D0-983A-00C04FC29E33" ID="DC1">  
   <PARAM NAME="SQL" VALUE="SELECT * FROM Authors">  
   <PARAM NAME="Connect" VALUE="DSN=Pubs;">  
   <PARAM NAME="Server" VALUE="https://yourServer/">  
</OBJECT>  
...  
<SCRIPT LANGUAGE="VBScript">  
  
Sub RDSTutorial2A()  
   Dim RS  
   DC1.Refresh  
   Set RS = DC1.Recordset  
...

Step 2b - Invoke the server program with RDSServer.DataFactory

Step 3 - Server obtains a Recordset

Step 4 - Server returns the Recordset

Set RS = DF1.Query("DSN=Pubs;", "SELECT * FROM Authors")

Step 5 - DataControl is made usable by visual controls

' Assign the returned recordset to the DataControl.  
  
DC1.SourceRecordset = RS

Step 6a - Changes are sent to the server with RDS.DataControl

This example is merely a comment demonstrating how the RDS.DataControl performs updates.

<OBJECT CLASSID="clsid:BD96C556-65A3-11D0-983A-00C04FC29E33" ID="DC1">  
   <PARAM NAME="SQL" VALUE="SELECT * FROM Authors">  
   <PARAM NAME="Connect" VALUE="DSN=Pubs;">  
   <PARAM NAME="Server" VALUE="https://yourServer/">  
</OBJECT>  
...  
<SCRIPT LANGUAGE="VBScript">  
  
Sub RDSTutorial6A()  
Dim RS  
DC1.Refresh  
...  
Set RS = DC1.Recordset  
' Edit the Recordset object...  
' The SERVER and CONNECT properties are already set from Step 2A.  
Set DC1.SourceRecordset = RS  
...  
DC1.SubmitChanges

Step 6b - Changes are sent to the server with RDSServer.DataFactory

DF.SubmitChanges "DSN=Pubs", RS  
  
End Sub  
</SCRIPT>  
</BODY>  
</HTML>

This is the end of the tutorial.

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